Sulfonated substantiallly random interpolymer-based absorbent materials

ABSTRACT

The present invention pertains to absorbent polymer composition comprising A) one or more sulfonated substantially random interpolymers comprising repeating units derived from; a) ethylene and/or one or more alpha olefins; b) one or more sulfonated vinyl or vinylidene aromatic monomers; c) one or more vinyl or vinylidene aromatic monomers, or a combination of one or more vinyl or vinylidene aromatic monomers and one or more sterically hindered aliphatic or cycloaliphatic vinyl or vinylidene monomers; and optionally, B) one or more polymers other than said sulfonated substantially random interpolymer. Uses of the compositions include the preparation of absorbent foams, fibers films and membranes for the preparation of absorbent articles for personal hygiene. These include diapers, sanitary napkins adult incontinence pads, and highly absorbent wipes, and dust pickups.

CROSS REFERENCED TO RELATED APPLICATIONS

[0001] This application is a 371 of PCT/US01/23511 filed Jul. 26, 2001.which claims priority to previously filed U.S. Provisional PatentApplication Serial No. 60/221,846, filed Jul. 28, 2000, both of whichare incorporated by reference herein in their entirety.

FEDERALLY SPONSORED RESEARCH STATEMENT

[0002] Not applicable.

REFERENCE TO MICROFICHE APPENDIX

[0003] Not applicable.

FIELD OF THE INVENTION

[0004] This present invention describes absorbent compositionscomprising sulfonated substantially random interpolymers. The sulfonatedsubstantially random interpolymers can be used either alone or as blendswith other polymers, and can be in either the sulfonic acid form, or asa neutralized or partially neutralized sulfonate salt. Another featureof the present invention is a process to prepare the sulfonatedsubstantially random interpolymers, comprising the use of a hydrocarbonswelling agent, prior to or coincident with, exposure to the sulfonatingagent. The sulfonated substantially random interpolymers or blendstherefrom can be used to prepare structures such as pellets, film,ribbon, sheet, strand or fiber, or closed and open cell foams, andfabricated articles therefrom.

BACKGROUND OF THE INVENTION

[0005] The generic class of substantially random α-olefin/vinyl orvinylidene aromatic monomer interpolymers, and their preparation, areknown in the art, such as described in EP 416 815 A2, the entirecontents of which are herein incorporated by reference. These materialsoffer a wide range of material structures and properties, which makesthem useful for varied applications.

[0006] The structure, thermal transitions and mechanical properties ofsubstantially random interpolymers of ethylene and styrene containing upto 50 mole percent styrene have been described (see Y. W. Cheung, M. J.Guest; Proc. Antec '96 pages 1634-1637). These polymers were found tohave glass transitions in the range −20° C. to +35° C., and showcrystallinity below 25 mole percent styrene incorporation, and nomeasurable crystallinity above 25 mole percent styrene incorporation,that is, they are essentially amorphous. This ability to tailor theproperties of the substantially random interpolymers by varying therelative amount of alpha olefin and vinyl or vinylidene aromatic monomercontent provides a great deal of flexibility in tailoring theirproperties for a particular end use application. For example, copendingU.S. application Ser. No. 09/317,389 filed on May 24, 1999 and PCTPublication WO 99/64500 (the entire contents of both of which are hereinincorporated by reference) describes the use of substantially randominterpolymers in formable membranes. Also, copending U.S. applicationSer. No. 08/991,036 filed on Dec. 16 1997, and PCT Publication WO99/31176 (the entire contents of both of which are herein incorporatedby reference) describes the use of substantially random interpolymers inthe form of barrier membranes for retarding gas migration.

[0007] Although of utility in their own right, Industry is constantlyseeking to improve the applicability of these interpolymers. There are anumber of applications where the ability to absorb or transport water orions such as protons, would be highly advantageous if combined with theflexibility of being able to tailor the product properties of thesubstantially random interpolymers.

[0008] In order to facilitate water migration (for water absorbentapplications) or proton transfer (for electrochemical applications),polystyrene and styrenic block copolymers are often sulfonated at thearomatic ring. U.S. Pat. Nos. 5,468,574 5,468,574 and 5,679,482 (theentire contents of both of which are incorporated herein by reference)disclose ion-conducting membranes prepared from polymers composed ofsulfonated hydrogenated block copolymers of styrene and butadiene.

[0009] For certain applications, it would be preferable if thesulfonated aromatic rings be randomly dispersed throughout the polymerchains and, in order to precisely tailor the resulting productproperties, that the sulfonation be done in a controlled fashion suchthat all degrees of sulfonation can be attained including surfacesulfonation, bulk sulfonation or anything in between. In contrast, quitethe opposite is desirable for ionomer applications. These require bothlow sulfonation conversion, (i.e. <approximately 10 percentapproximately 10 percent) and localized sulfonation resulting in ionicdomains called clusters, which propagate physical crosslinks at lowlevels.

[0010] This degree of control of the amount of sulfonation, the location(surface or bulk) and control over the dispersion cannot be accomplishedusing block or graft styrene copolymers. Such copolymers have thearomatic rings in discrete regions or domains within the polymer chains,or as in random styrenic copolymers, a random placement of the aromaticrings which is difficult to control. In high conversion sulfonation ofpolystyrene (or blocky styrenic copolymers), once a phenyl group issulfonated, it acts as a polar director toward nearest neighbor phenylgroup sulfonation. This results in blocky sulfonated segments early insulfonation and can also result in higher melt viscosities, thus slowingthe overall rate of sulfonation.

[0011] The majority of such sulfonated styrenic compositions to datehave been prepared either in (a) a single phase system (uncrosslinkedpolymer in solution) or (b) a two phase system (crosslinked beads,fiber, etc). The most common solvents/swelling agents are thehalogenated hydrocarbons such as methylene chloride, ethylenedichloride, and chlorobenzene.

[0012] PCT Publication WO 99/20691 (the entire contents of which areherein incorporated by reference) discloses surface sulfonatedsubstantially random interpolymers and articles therefrom as in the formof sheet or film, and that films and sheets made from such polymers canbe used to “improve the barrier properties of articles to gases”. Thesulfonation of any particular phenyl group in such substantially randominterpolymers has minimal directing effect on the sulfonation of otherphenyl group in the interpolymer.

[0013] For substantially random interpolymers, which are uncrosslinked,we have surprisingly found that simple C₃-C₂₀ aliphatic andcycloaliphatic hydrocarbons such as hexanes, heptane, octane,cyclohexane and the like, provide rapid swelling capability withoutdissolution over a wide range of swelling rates. This allows for the useof sulfonation processes, which have a wide variation in residence timesand thus can be either batch or continuous processes. Thus by judiciouschoice of process residence time and/or swelling agent one can controlthe degree of sulfonation of the substantially random interpolymers in apolymer (or fabricated article therefrom) such that one can achieveeverything from simple surface sulfonation to almost complete bulksulfonation.

[0014] In addition, use of the materials and processes of the presentinvention allows for the preparation of absorbent articles that exhibitan improved balance of wicking and absorption kinetics. This is providedby variation of both the nature of the substantially randominterpolymer-based starting material (crystalline or amorphous,ionomeric or not, and degree of gel domains) as well as control of theprocess conditions and degree of sulfonation. Thus both variables canthen be optimized to yield improvements in polymer performance andeconomics.

[0015] In one preferred embodiment of the present invention, suchprocesses are applied to the manufacture of absorbent fibers comprisingthe sulfonated substantially random interpolymers. Existing technologyfor the preparation of absorbent fibers typically involves dry spinning(where a solution of polymer is spun and the solvent is evaporated ismore costly). In addition, existing technology is limited to simpleprocess control for variation in wicking/absorbent performance and thepolymer composition typically has limited variability. The use of thesulfonated substantially random interpolymer-based materials forabsorbent and/or superabsorbent applications represents a simple, lowcost process in comparison to existing technology.

[0016] Thus the absorbent fibers of the present invention can beinitially formed comprising the substantially random polymers whichfibers can then be subsequently sulfonated to the required degree.Alternatively the fibers can be directly fabricated from the sulfonatedsubstantially random interpolymers.

[0017] Similarly in the preparation of fabricated articles from theabsorbent materials of the present invention, it is possible to eitherprepare the fabricated article from one or more sulfonated substantiallyrandom interpolymers (or blend therefrom). It is also possible toprepare the fabricated article from one or more substantially randominterpolymers (or blend therefrom) with subsequent sulfonation.

[0018] In an especially preferred embodiment, the use of the materialsand processes of the present invention allows the design ofbicomponent/biconstituent materials comprising the sulfonatedsubstantially random interpolymers for performance and costoptimization.

SUMMARY OF THE INVENTION

[0019] The present invention pertains to an absorbent polymercomposition comprising

[0020] A) one or more sulfonated substantially random interpolymerscomprising repeating units derived from;

[0021] a) ethylene and/or one or more alpha olefins;

[0022] b) one or more sulfonated vinyl or vinylidene aromatic monomers;

[0023] c) one or more vinyl or vinylidene aromatic monomers, or acombination of one or more vinyl or vinylidene aromatic monomers and oneor more sterically hindered aliphatic or cycloaliphatic vinyl orvinylidene monomers; and optionally

[0024] B) one or more polymers other than said sulfonated substantiallyrandom interpolymer.

[0025] Uses of the compositions include the preparation of absorbentfoams, fibers films and membranes as well as the preparation ofabsorbent fabricated articles for personal hygiene. These includediapers, sanitary napkins, adult incontinence pads, and highly absorbentwipes, and dust pickups.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Not applicable.

DETAILED DESCRIPTION OF THE INVENTION

[0027] All references herein to elements or metals belonging to acertain Group refer to the Periodic Table of the Elements published andcopyrighted by CRC Press, Inc., 1989. Also any reference to the Group orGroups shall be to the Group or Groups as reflected in this PeriodicTable of the Elements using the IUPAC system for numbering groups.

[0028] Any numerical values recited herein include all values from thelower value to the upper value in increments of one unit provided thatthere is a separation of at least 2 units between any lower value andany higher value. As an example, if it is stated that the amount of acomponent or a value of a process variable such as, for example,temperature, pressure, time and the like is, for example, from 1 to 90,preferably from 20 to 80, more preferably from 30 to 70, it is intendedthat values such as 15 to 85, 22 to 68, 43 to 51, 30 to 32 etc. areexpressly enumerated in this specification. For values which are lessthan one, one unit is considered to be 0.0001, 0.001, 0.01 or 0.1 asappropriate. These are only examples of what is specifically intendedand all possible combinations of numerical values between the lowestvalue and the highest value enumerated are to be considered to beexpressly stated in this application in a similar manner.

[0029] The term “hydrocarbyl” as employed herein means any aliphatic,cycloaliphatic, aromatic, aryl substituted aliphatic, aryl substitutedcycloaliphatic, aliphatic substituted aromatic, or aliphatic substitutedcycloaliphatic groups.

[0030] The term “hydrocarbyloxy” means a hydrocarbyl group having anoxygen linkage between it and the carbon atom to which it is attached.

[0031] The term “interpolymer” is used herein to indicate a polymerwherein at least two different monomers are polymerized to make theinterpolymer. This includes copolymers, terpolymers, etc.

[0032] The term “absorbent polymer composition” is used herein toindicate a polymer or blend of polymers able to take up at least 5,preferably at least 50, more preferably at least 100 percent of its ownweight when placed in water.

[0033] The term “superabsorbent polymer” is used herein in theconventional sense in reference to polymeric materials that imbibe fluidand thereby form a swollen hydrogel. That is, a superabsorbent polymeris a hydrogel-forming polymeric gelling agent. In particular, thepolymeric gelling agent comprises a substantially water-insoluble,partially neutralized, hydrogel-forming polymer material that istypically prepared from polymerizable, unsaturated, acid-containingmonomers and often grafted onto other types of polymer moieties and thenslightly crosslinked with agents such as, for example, triallyl amine.See, for example, U.S. Pat. No. 5,061,259 and U.S. Pat. No. 4,654,039,the disclosures of which are incorporated herein by reference, foradditional description pertaining to superabsorbent polymers.Superabsorbent polymer is referenced herein by the acronym “SAP”.

[0034] The term “absorbent fabricated article” “is used herein toindicate an article such as a foam, fiber, film, membrane, or anyarticle prepared therefrom which in turn comprises the absorbent polymercompositions of the present invention. More specifically, the termrefers to devices that are placed against or in proximity to the body ofthe wearer to absorb and contain the various exudates discharged fromthe body. These exudates include, but are not limited to urine, menses,vaginal discharge, sweat and feces. The devices include, but are notlimited to absorbent articles for personal hygiene such as diapers,sanitary napkins and adult incontinence pads,

[0035] The term “substantially random” (in the substantially randominterpolymer comprising polymer units derived from ethylene and one ormore α-olefin monomers with one or more vinyl or vinylidene aromaticmonomers and/or sterically hindered aliphatic or cycloaliphatic vinyl orvinylidene monomers) as used herein means that the distribution of themonomers of said interpolymer can be described by the Bernoullistatistical model or by a first or second order Markovian statisticalmodel, as described by J. C. Randall in Polymer Sequence Determination,Carbon-13 NMR Method, Academic Press New York, 1977, pp. 71-78.Preferably, substantially random interpolymers do not contain more than15 percent of the total amount of vinyl aromatic monomer in blocks ofvinyl aromatic monomer of more than 3 units. More preferably, theinterpolymer is not characterized by a high degree of eitherisotacticity or syndiotacticity. This means that in the carbon⁻¹³ NMRspectrum of the substantially random interpolymer the peak areascorresponding to the main chain methylene and methine carbonsrepresenting either meso diad sequences or racemic diad sequences shouldnot exceed 75 percent of the total peak area of the main chain methyleneand methine carbons.

[0036] The term “degree of sulfonation” or “percent conversion” are usedinterchangeably and as used herein refer to the percentage of thearomatic content of the aromatic groups in the unsulfonatedsubstantially random interpolymer which are converted to sulfonatedaromatic groups on sulfonation (on a scale of 0 to 100). It iscalculated from the percent weight gain of the interpolymer onsulfonation using the following formula:

Conversion=[(percent weight gain)(MW _(va))]/[(MW _(svas) −MW _(va))(VA_(f))] where;

[0037] MW_(vas)=vinyl aromatic sulfonic acid or sulfonate salt molecularweight

[0038] MW_(va)=vinyl aromatic molecular weight

[0039] VA_(f)=weight fraction of vinyl aromatic in startingsubstantially random interpolymer.

[0040] Thus for a substantially random interpolymer of ethylene andstyrene containing 75 wt percent styrene and converted into the sodiumsulfonate derivative, the calculation becomes:

% Conversion=[(% weight gain)(104)]/[(206−104)(0.75)]=(% weightgain)(1.36)×100/1

[0041] The term “homofil” as used herein refers to fiber which has asingle polymer region or domain and does not have any other distinctpolymer regions (as do bicomponent fibers), even though the polymeritself may have a plurality of phases or microphases.

[0042] The term “meltblown” is used herein in the conventional sense torefer to fibers formed by extruding the molten elastic compositionthrough a plurality of fine, usually circular, die capillaries as moltenthreads or filaments into converging high velocity gas streams (e.g.air) which function to attenuate the threads or filaments to reduceddiameters. Thereafter, the filaments or threads are carried by the highvelocity gas streams and deposited on a collecting surface to form a webof randomly dispersed fibers with average diameters generally smallerthan 10 microns.

[0043] The term “spunbond” is used herein in the conventional sense torefer to fibers formed by extruding the molten elastic composition asfilaments through a plurality of fine, usually circular, die capillariesof a spinneret with the diameter of the extruded filaments then beingrapidly reduced and thereafter depositing the filaments onto acollecting surface to form a web of randomly dispersed spunbond fiberswith average diameters generally between about 7 and about 30 microns.

[0044] The term “nonwoven” as used herein and in the conventional sensemeans a web or fabric having a structure of individual fibers or threadswhich are randomly interlaid, but not in an identifiable manner as isthe case for a knitted fabric.

[0045] The term “conjugated” refers to fibers which have been formedfrom at least two polymers extruded from separate extruders butmeltblown or spun together to form one fiber.

[0046] The Substantially Random Interpolymers

[0047] The interpolymers used in the present invention include thesubstantially random interpolymers, which are then sulfonated eitherprior to or after fabrication. The substantially random interpolymersare prepared by polymerizing i) ethylene and/or one or more α-olefinmonomers and ii) one or more vinyl or vinylidene aromatic monomersand/or one or more sterically hindered aliphatic or cycloaliphatic vinylor vinylidene monomers, and optionally iii) other polymerizableethylenically unsaturated monomer(s). Suitable α-olefins include forexample, α-olefins containing from 3 to about 20, preferably from 3 toabout 12, more preferably from 3 to about 8 carbon atoms. Particularlysuitable are ethylene, propylene, butene-1,4-methyl-1-pentene, hexene-1or octene-1 or ethylene in combination with one or more of propylene,butene-1,4-methyl-1-pentene, hexene-1 or octene-1. These α-olefins donot contain an aromatic moiety.

[0048] Suitable vinyl or vinylidene aromatic monomers, which can beemployed to prepare the interpolymers, include, for example, thoserepresented by the following formula:

[0049] wherein R¹ is selected from the group of radicals consisting ofhydrogen and alkyl radicals containing from 1 to about 4 carbon atoms,preferably hydrogen or methyl; each R² is independently selected fromthe group of radicals consisting of hydrogen and alkyl radicalscontaining from 1 to about 4 carbon atoms, preferably hydrogen ormethyl; Ar is a phenyl group or a phenyl group substituted with from 1to 5 substituents selected from the group consisting of halo,C₁₋₄-alkyl, and C₁₋₄-haloalkyl; and n has a value from zero to about 4,preferably from zero to 2, most preferably zero. Exemplary vinyl orvinylidene aromatic monomers include styrene, vinyl toluene,α-methylstyrene, t-butyl styrene, chlorostyrene, including all isomersof these compounds, and the like. Particularly suitable such monomersinclude styrene and lower alkyl- or halogen-substituted derivativesthereof. Preferred monomers include styrene, α-methyl styrene, the loweralkyl-(C₁-C₄) or phenyl-ring substituted derivatives of styrene, such asfor example, ortho-, meta-, and para-methylstyrene, the ring halogenatedstyrenes, para-vinyl toluene or mixtures thereof, and the like. A morepreferred aromatic vinyl monomer is styrene.

[0050] By the term “sterically hindered aliphatic or cycloaliphaticvinyl or vinylidene compounds”, it is meant addition polymerizable vinylor vinylidene monomers corresponding to the formula:

[0051] wherein A¹ is a sterically bulky, aliphatic or cycloaliphaticsubstituent of up to 20 carbons, R¹ is selected from the group ofradicals consisting of hydrogen and alkyl radicals containing from 1 toabout 4 carbon atoms, preferably hydrogen or methyl; each R² isindependently selected from the group of radicals consisting of hydrogenand alkyl radicals containing from 1 to about 4 carbon atoms, preferablyhydrogen or methyl; or alternatively R¹ and A¹ together form a ringsystem. Preferred aliphatic or cycloaliphatic vinyl or vinylidenecompounds are monomers in which one of the carbon atoms bearingethylenic unsaturation is tertiary or quaternary substituted. Examplesof such substituents include cyclic aliphatic groups such as cyclohexyl,cyclohexenyl, cyclooctenyl, or ring alkyl or aryl substitutedderivatives thereof, tert-butyl, norbornyl, and the like. Most preferredaliphatic or cycloaliphatic vinyl or vinylidene compounds are thevarious isomeric vinyl-ring substituted derivatives of cyclohexene andsubstituted cyclohexenes, and 5-ethylidene-2-norbornene. Especiallysuitable are 1-, 3-, and 4-vinylcyclohexene and5-ethylidene-2-norbornene. Simple linear non-branched α-olefinsincluding for example, α-olefins containing from 3 to about 20 carbonatoms such as propylene, butene-1,4-methyl-1-pentene, hexene-1 oroctene-1 are not examples of sterically hindered aliphatic orcycloaliphatic vinyl or vinylidene compounds.

[0052] Other optional polymerizable ethylenically unsaturated monomer(s)include norbornene and C₁₋₁₀ alkyl or C₆₋₁₀ aryl substitutednorbornenes, with an exemplary interpolymer beingethylene/styrene/norbornene.

[0053] The most preferred substantially random interpolymers are theethylene/styrene, ethylene/propylene/styrene,ethylene/styrene/norbornene, and ethylene/propylene/styrene/norborneneinterpolymers.

[0054] The substantially random interpolymers include the pseudo-randominterpolymers as described in EP-A-0,416,815 by James C. Stevens et al.and U.S. Pat. No. 5,703,187 by Francis J. Timmers, both of which areincorporated herein by reference in their entirety. The substantiallyrandom interpolymers can be prepared by polymerizing a mixture ofpolymerizable monomers in the presence of one or more metallocene orconstrained geometry catalysts in combination with various cocatalysts.Preferred operating conditions for such polymerization reactions arepressures from atmospheric up to 3000 atmospheres and temperatures from−30° C. to 200° C. Polymerizations and unreacted monomer removal attemperatures above the autopolymerization temperature of the respectivemonomers may result in formation of some amounts of homopolymerpolymerization products resulting from free radical polymerization.

[0055] Examples of suitable catalysts and methods for preparing thesubstantially random interpolymers are disclosed in U.S. applicationSer. No. 702,475, filed May 20, 1991 (EP-A-514,828); as well as U.S.Pat. Nos. 5,055,438; 5,057,475; 5,096,867; 5,064,802; 5,132,380;5,189,192; 5,321,106; 5,347,024; 5,350,723; 5,374,696; 5,399,635;5,470,993; 5,703,187; and 5,721,185 all of which patents andapplications are incorporated herein by reference.

[0056] The substantially random α-olefin/vinyl aromatic interpolymerscan also be prepared by the methods described in JP 07/278230 employingcompounds shown by the general formula

[0057] where Cp¹ and Cp² are cyclopentadienyl groups, indenyl groups,fluorenyl groups, or substituents of these, independently of each other;R¹ and R² are hydrogen atoms, halogen atoms, hydrocarbon groups withcarbon numbers of 1-12, alkoxyl groups, or aryloxyl groups,independently of each other; M is a group IV metal, preferably Zr or Hf;most preferably Zr; and R³ is an alkylene group or silanediyl group usedto cross-link Cp¹ and Cp².

[0058] The substantially random α-olefin/vinyl aromatic interpolymerscan also be prepared by the methods described by John G. Bradfute et al.(W. R. Grace & Co.) in WO 95/32095; by R. B. Pannell (Exxon ChemicalPatents, Inc.) in WO 94/00500; and in Plastics Technology, p. 25(September 1992), all of which are incorporated herein by reference intheir entirety.

[0059] Also suitable are the substantially random interpolymers whichcomprise at least one α-olefin/vinyl aromatic/vinyl aromatic/α-olefintetrad disclosed in U.S. application Ser. No. 08/708,869 filed Sep. 4,1996 and WO 98/09999 both by Francis J. Timmers et al., the entirecontents of both of which are herein incorporated by reference. Theseinterpolymers contain additional signals in their carbon-13 NMR spectrawith intensities greater than three times the peak to peak noise. Thesesignals appear in the chemical shift range 43.70-44.25 ppm and 38.0-38.5ppm. Specifically, major peaks are observed at 44.1, 43.9, and 38.2 ppm.A proton test NMR experiment indicates that the signals in the chemicalshift region 43.70-44.25 ppm are methine carbons and the signals in theregion 38.0-38.5 ppm are methylene carbons.

[0060] Further preparative methods for the interpolymers used in thepresent invention have been described in the literature. Longo andGrassi (Makromol. Chem., Volume 191, pages 2387 to 2396 [1990]) andD'Anniello et al. (Journal of Applied Polymer Science, Volume 58, pages1701-1706 [1995]) reported the use of a catalytic system based onmethylalumoxane (MAO) and cyclopentadienyltitanium trichloride (CpTiCl₃)to prepare an ethylene-styrene copolymer. Xu and Lin (Polymer Preprints,Am. Chem. Soc., Div. Polym. Chem.) Volume 35, pages 686,687 [1994]) havereported copolymerization using a MgCl₂/TiCl₄/NdCl₃/Al(iBu)₃ catalyst togive random copolymers of styrene and propylene. Lu et al (Journal ofApplied Polymer Science, Volume 53, pages 1453 to 1460 [1994]) havedescribed the copolymerization of ethylene and styrene using aTiCl₄/NdCl₃/MgCl₂/Al(Et)₃ catalyst. Sernetz and Mulhaupt, (Macromol.Chem. Phys., v. 197, pp. 1071-1083, 1997) have described the influenceof polymerization conditions on the copolymerization of styrene withethylene using Me₂Si(Me₄Cp)(N-tert-butyl)TiCl₂/methylaluminoxaneZiegler-Natta catalysts. Copolymers of ethylene and styrene produced bybridged metallocene catalysts have been described by Arai, Toshiaki andSuzuki (Polymer Preprints, Am. Chem. Soc., Div. Polym. Chem.) Volume 38,pages 349, 350 [1997]) and in U.S. Pat. No. 5,652,315, issued to MitsuiToatsu Chemicals, Inc. The manufacture of α-olefin/vinyl aromaticmonomer interpolymers such as propylene/styrene and butene/styrene aredescribed in U.S. Pat. No. 5,244,996, issued to Mitsui PetrochemicalIndustries Ltd or U.S. Pat. No. 5,652,315 also issued to MitsuiPetrochemical Industries Ltd or as disclosed in DE 197 11 339 A1 andU.S. Pat. No. 5,883,213 to Denki Kagaku Kogyo KK. All the above methodsdisclosed for preparing the interpolymer component are incorporatedherein by reference. Also, although of high isotacticity and thereforenot “substantially random”, the random copolymers of ethylene andstyrene as disclosed in Polymer Preprints, Vol. 39, No. 1, March 1998 byToru Aria et al. can also be employed as blend components for the foamsof the present invention.

[0061] While preparing the substantially random interpolymer, an amountof atactic vinyl aromatic homopolymer may be formed due tohomopolymerization of the vinyl aromatic monomer at elevatedtemperatures. The presence of vinyl aromatic homopolymer is in generalnot detrimental for the purposes of the present invention and can betolerated. The vinyl aromatic homopolymer may be separated from theinterpolymer, if desired, by extraction techniques such as selectiveprecipitation from solution with a non solvent for either theinterpolymer or the vinyl aromatic homopolymer. For the purpose of thepresent invention it is preferred that no more than 30 weight percent,preferably less than 20 weight percent based on the total weight of theinterpolymers of atactic vinyl aromatic homopolymer is present.

[0062] The Sulfonated Substantially Random Interpolymers

[0063] The substantially random interpolymers can be sulfonated by anysuitable means known in the art for sulfonating aromatic ring compoundsincluding using so called “wet” (sulfuric acid, oleum, chlorosulphonicacid, SO₃ complexes) or gaseous (air sulfonation, SO3 vapor phasesulfonation) reagents.

[0064] A preferred method involves contacting the substantially randominterpolymer with a fluid phase of sulfur trioxide, present as minorcomposition (less than 50 percent by weight) in another carrier gas suchas nitrogen or air at a temperature of from about 20° C. to about 200°C., preferably from about 50° C. to about 150° C., more preferably fromabout 80° C. to about 150° C. Optionally, a C₁-C₂₀, preferably C₁-C₁₀,more preferably C₁-C₆ hydrocarbon swelling agent (including but notexclusively ethane, propane, butane, pentane, hexane, and cyclohexane)can be incorporated with the carrier gas or, alternatively theinterpolymer can be exposed to the swelling agent prior to sulfonation.

[0065] The substantially random interpolymer can also be sulfonated bycontacting with a liquid phase of oleum (5-60 percent sulfur trioxidedissolved in sulfuric acid), at a temperature of from about −20° C. toabout 100° C., preferably from about 0° C. to about 80° C., morepreferably from about 0° C. to about 50° C. Optionally, the polymer canbe exposed to a a C₁-C₂₀, preferably C₁-C₁₀, more preferably C₁-C₆hydrocarbon swelling agent (including, but not exclusively, pentane,hexane, and cyclohexane) either prior to or concurrently withsulfonation.

[0066] Another suitable method is that described by Turbuk in U.S. Pat.No. 3,072,618 which is incorporated herein by reference in its entirety.The substantially random interpolymer is sulfonated by contacting with asulfonating complex comprising the reaction product of about 2 to about4 moles of sulfur trioxide and 1 mole of a lower trialkyl phosphate orphosphite at a temperature of from about 25° C. to about 100° C.,preferably from about 50° C. to about 83° C., more preferably from about75° C. to about 83° C. followed by recovering the resultant sulfonatedpolymer. Sulfur trioxide can also be supplied in the form ofchlorosulfonic acid or fuming sulfuric acid. Particularly suitabletrialkyl phosphates include trimethyl phosphate, triethyl phosphate,tripropyl phosphate, tributyl phosphate, trimethyl phosphite, triethylphosphite, tripropyl phosphite, tributyl phosphate, hydrogen phosphate,diethyl hydrogen phosphate, dimethyl hydrogen phosphite, diethylhydrogen phosphite, methyl dihydrogen phosphate, ethyl dihydrogenphosphate, methyl dihydrogen phosphite, ethyl dihydrogen phosphite, anycombination thereof and the like.

[0067] Another method of sulfonation is that described by H. S.Makowski, R. D. Lundberg, and G. H. Singhal in U.S. Pat. No. 3,870,841which is incorporated herein by reference in its entirety. In thismethod, a mixed anhydride is prepared by mixing sulfuric acid withacetic anhydride at a temperature of from about −70° C. to about 130° C.(preferably between −20 to about 20° C.) followed by adding this mixtureto a solution of the interpolymer in a chlorinated solvent such as, forexample dichloroethane, methylene chloride, chloroform,tetrachloroethane, trichloroethane or combinations thereof at atemperature of from about −20° C. to about 100° C.

[0068] The salts of the sulfonated interpolymers can be prepared byreacting with a neutralizing agent or base (ammonia, alkylamines,ammonium hydroxide, sodium hydroxide, etc.) in a solvent or as a gasphase at temperatures of from about −20° C. to about 100° C., preferablyfrom about 40° C. to about 100° C., more preferably from about 60° C. toabout 80° C. for a period of time to convert essentially all of the SO₃Hgroups to the neutralized salt, —SO₃Me (where Me is the counterion).This time is usually from about 0.01 to about 240, preferably from about1 to about 60, more preferably from about 5 to about 30 minutes. Me caninclude a group 1, 2, 7, 11 or 12 metals of the Periodic Table ofElements. The amount of the neutralizing agent employed is that which issufficient to convert substantially all of the sulfonate groups to theneutralized salt, usually from about 1 to about 1.5, preferably fromabout 1 to about 1.1, more preferably about 1 mole of the neutralizingagent per mole of sulfonate group present in the interpolymer. Theamount of solvent employed is that amount sufficient to create asubstantially homogeneous mixture, which can range from about 5 to about95, preferably from about 10 to about 80, more preferably from about 15to about 75 percent by weight based on the combined weight of themixture.

[0069] The sulfonated substantially random interpolymers comprise fromabout 35 to about 98.5 mol percent of polymer units derived fromethylene and/or said α-olefin which comprises at least one of propylene,4-methyl-1-pentene, butene-1, hexene-1 or octene-1; and from about 1.5to about 65 mol percent of polymer units derived from one or moresulfonated vinyl aromatic monomers which are mono substituted witheither a sulfonic acid group or a sulfonic acid salt represented by thefollowing formula;

[0070] wherein R¹ is selected from the group of radicals consisting ofhydrogen and alkyl radicals containing from 1 to about 4 carbon atoms,each R² is independently selected from the group of radicals consistingof hydrogen and alkyl radicals containing from 1 to about 4 carbonatoms, Ar is a phenyl group or a phenyl group substituted with from 1 to5 substituents selected from the group consisting of halo, C₁₋₄-alkyl,and C₁₋₄-haloalkyl; and n has a value from zero to about 4, and X ishydrogen, a group 1, 2, 7, 11 or 12 metal ion, an ammonium salt NR′₄ ⁺where R′ is hydrogen or a C3-C20 alkyl or a combination thereof;Preferably suitable metal salts which can be employed herein include thesalts formed from group 1, 2, 7, 11 or 12 metals as well as the ammonium(NH₄ ⁺) salts. Particularly suitable metals of group 1, 2, 7, 11, or 12include Na, K, Li, Co, Cu, Mg, Ca, Mn, or Zn. Also suitable are thehydroxides of such metals. Particularly suitable salts and hydroxidesinclude the hydroxides, acetates, hexanoates, and oxides of Na, Li, K,Ca, Mg, Cu, Co, Zn Al, NH₄+, and any combination thereof and the like.Also suitable are the hydrates of the aforementioned salts.

[0071] In the case where the sulfonation conversion is less than 100percent, the sulfonated substantially random interpolymers would thusalso comprise polymer units derived from the starting substantiallyrandom interpolymer namely ethylene and/or one or more α-olefin monomersand ii) one or more vinyl or vinylidene aromatic monomers and/or one ormore sterically hindered aliphatic or cycloaliphatic vinyl or vinylidenemonomers, and optionally iii) other polymerizable ethylenicallyunsaturated monomer(s).

[0072] Additional Blend Component(s).

[0073] The polymers used to prepare the absorbent compositions of thepresent invention can also comprise one or more polymers other than thesulfonated substantially random interpolymer. These additional polymerscan comprise homogenous α-olefin homopolymer or interpolymers comprisingpolypropylene, propylene/C₄-C₂₀ α-olefin copolymers, polyethylene, andethylene/C₃-C₂₀ α-olefin copolymers, the interpolymers can be eitherheterogeneous ethylene/α-olefin interpolymers, preferably aheterogeneous ethylene/C₃-C₈ α-olefin interpolymer, most preferably aheterogeneous ethylene/octene-1 interpolymer or homogeneousethylene/α-olefin interpolymers, including the substantially linearethylene/α-olefin interpolymers, preferably a substantially linearethylene/α-olefin interpolymer, most preferably a substantially linearethylene/C₃-C₈ α-olefin interpolymer; or a heterogeneousethylene/α-olefin interpolymer; or a thermoplastic olefin, preferably anethylene/propylene rubber (EPM) or ethylene/propylene diene monomerterpolymer (EPDM) or isotactic polypropylene, most preferably isotacticpolypropylene; or a styreneic block copolymer, preferablystyrene-butadiene (SB), styrene-isoprene(SI), styrene-butadiene-styrene(SBS), styrene-isoprene-styrene (SIS) or styrene-ethylene/butene-styrene(SEBS) block copolymer, most preferably a styrene-butadiene-styrene(SBS) copolymer; or styrenic homopolymers or copolymers, preferablypolystyrene, high impact polystyrene, polyvinyl chloride, copolymers ofstyrene and at least one of acrylonitrile, methacrylonitrile, maleicanhydride, or α-methyl styrene, most preferably polystyrene, orelastomers, preferably polyisoprene, polybutadiene, natural rubbers,ethylene/propylene rubbers, ethylene/propylene diene (EPDM) rubbers,styrene/butadiene rubbers, thermoplastic polyurethanes, most preferablythermoplastic polyurethanes; or engineering thermosplastics, preferablypoly(methylmethacrylate) (PMMA), cellulosics, nylons, poly(esters),poly(acetals); poly(amides), the poly(arylate), aromatic polyesters,poly(carbonate), poly(butylene) and polybutylene and polyethyleneterephthalates, most preferably poly(methylmethacrylate) (PMMA), andpoly(esters).

[0074] Especially preferred as the other polymer component is one ormore existing water retentive polymers. Such polymers can comprisenonionic polymers like polyacrylamide, polyethylene oxide, polyvinylalcohol; anoionic polymers and their neutralized salts includingpolyacrylic acid, graft copolymers including starch-g-polyacrylic acid,poly(vinyl alcohol-g-polyacrylic acid), hydrolyzedstarch-g-poly(acrylonitrile), carboxymethylcellulose, alginic acid;cationic polymers including poly(diallyldimethylammonium chloride,polyvinylpyridine, cationic starches, and hydroyzed chitin. Thesematerials can be optionally crosslinked to prevent dissolution intowater.

[0075] Fillers

[0076] Also included as a potential component of the polymercompositions used in the present invention are various organic andinorganic fillers, the identity of which depends upon the type ofapplication for which the composition is to be utilized. The fillers canalso be included in the sulfonated substantially random interpolymer,component, the other polymer component and/or the overall blendcompositions employed in the present invention. Representative examplesof such fillers include organic and inorganic fibers such as those madefrom asbestos, boron, graphite, ceramic, glass, metals (such asstainless steel) or polymers (such as aramid fibers) talc, carbon black,carbon fibers, calcium carbonate, alumina trihydrate, glass fibers,marble dust, cement dust, clay, feldspar, silica or glass, fumed silica,alumina, magnesium oxide, magnesium hydroxide, antimony oxide, zincoxide, barium sulfate, aluminum silicate, magnesium aluminum silicate,calcium silicate, titanium dioxide, titanates, aluminum nitride, B₂O₃,nickel powder or chalk.

[0077] Other representative organic or inorganic, fiber or mineral,fillers include carbonates such as barium, calcium or magnesiumcarbonate; fluorides such as calcium or sodium aluminum fluoride;hydroxides such as aluminum hydroxide; metals such as aluminum, bronze,lead or zinc; oxides such as aluminum, antimony, magnesium or zincoxide, or silicon or titanium dioxide; silicates such as asbestos, mica,clay (kaolin or calcined kaolin), feldspar, glass (ground or flakedglass or hollow glass spheres or microspheres or beads, whiskers orfilaments), nepheline, perlite, pyrophyllite, talc or wollastonite;sulfates such as barium or calcium sulfate; metal sulfides; cellulose,in forms such as wood or shell flour; calcium terephthalate; and liquidcrystals. Also included are the various classes of fillers that act asanti-microbial agents. Mixtures of more than one such filler may be usedas well.

[0078] Other Additives

[0079] Additives such as antioxidants (e.g., hindered phenols such as,for example, Irganox™ 1010), phosphites (e.g., Irgafos™ 168) bothtrademarks of, and commercially available from, Ciba Geigy Corporation),U.V. stabilizers, cling additives (e.g., polyisobutylene), antiblockadditives, colorants, pigments, and the like are optionally alsoincluded in in the sulfonated substantially random interpolymer,component, the other polymer component and/or the overall blendcompositions employed in the present invention, to the extent that theydo not interfere with the enhanced properties discovered by Applicants.

[0080] Processing aids, which are also referred to herein asplasticizers, can also be included in the sulfonated substantiallyrandom interpolymer, component, the other polymer component and/or theoverall blend compositions employed in the present invention. Theseinclude the phthalates, such as dioctyl phthalate and diisobutylphthalate, natural oils such as lanolin, and paraffin, naphthenic andaromatic oils obtained from petroleum refining, and liquid resins fromrosin or petroleum feedstocks. Exemplary classes of oils useful asprocessing aids include white mineral oil (such as Kaydol™ oil(available from and a registered trademark of Witco), and Shellflex™ 371naphthenic oil (available from and a registered trademark of Shell OilCompany). Another suitable oil is Tuflo™ oil (available from and aregistered trademark of Lyondell).

[0081] Tackifiers, can also be included in the sulfonated substantiallyrandom interpolymer, component, the other polymer component and/or theoverall blend compositions employed in the present invention, to alterthe processing performance of a polymer and thus extend the availableapplication temperature window of the application. A suitable tackifiermay be selected on the basis of the criteria outlined by Hercules in J.Simons, Adhesives Age, “The HMDA Concept: A New Method for Selection ofResins”, November 1996. This reference discusses the importance of thepolarity and molecular weight of the resin in determining compatibilitywith the polymer. In the case of substantially random interpolymers ofat least one α-olefin and a vinyl aromatic monomer, preferred tackifierswill have some degree of aromatic character to promote compatibility,particularly in the case of substantially random interpolymers having ahigh content of the vinyl aromatic monomer.

[0082] Tackifying resins can be obtained by the polymerization ofpetroleum and terpene feedstreams and from the derivatization of wood,gum, and tall oil rosin. Several classes of tackifiers include woodrosin, tall oil and tall oil derivatives, and cyclopentadienederivatives, such as are described in United Kingdom patent applicationGB 2,032,439A. Other classes of tackifiers include aliphatic C₅ resins,polyterpene resins, hydrogenated resins, mixed aliphatic-aromaticresins, rosin esters, natural and synthetic terpenes, terpene-phenolics,and hydrogenated rosin esters.

[0083] The additives are advantageously employed in functionallyequivalent amounts known to those skilled in the art. For example, theamount of antioxidant employed is that amount which prevents the polymeror polymer blend from undergoing oxidation at the temperatures andenvironment employed during storage and ultimate use of the polymers.Such amount of antioxidants is usually in the range of from 0.01 to 10,preferably from 0.05 to 5, more preferably from 0.1 to 2 percent byweight based upon the weight of the polymer or polymer blend. Similarly,the amounts of any of the other enumerated additives are thefunctionally equivalent amounts such as the amount to render the polymeror polymer blend antiblocking, to produce the desired amount of fillerloading to produce the desired result, to provide the desired color fromthe colorant or pigment. Such additives are advantageously employed inthe range of from 0.05 to 50, preferably from 0.1 to 35, more preferablyfrom 0.2 to 20 percent by weight based upon the weight of the polymer orpolymer blend. Fillers, however can be advantageously employed inamounts up to about 90 percent by weight based on the weight of thepolymer or polymer blend.

[0084] The sulfonated substantially random interpolymers and blendstherefrom of the present invention can be available in a wide range ofstructures including but not limited to, fibers, films, sheet, andfoams, and fabricated articles therefrom

[0085] Preparation of Fibers Comprising the Sulfonated SubstantiallyRandom Interpolymers

[0086] In one embodiment of the present invention, the sulfonatedsubstantially random interpolymers are used to prepare absorbent fibers.The fibers can be prepared from the sulfonated substantially randominterpolymers using the methods described herein. Alternatively, thefibers can be prepared from the substantially random interpolymers andthen the resulting fiber can then be sulfonated either after or duringthe fiber manufacturing process, using the sulfonation processesdescribed herein. In such a post fiber sulfonation process, the natureand incorporation of the previously described swelling and sulfonationagents and reaction times can then be tailored to the particular fiberpreparation.

[0087] The main advantages of the sulfonated substantially randominterpolymers versus other polymers such as sulfonated polystyrene foruse in fibers are the improved physical properties such as flexibilityresulting from the occurrence of aromatic and ethylene and/or alphaolefin functionality in the polymer and their relative distributions.Polystyrene and sulfonated polystyrene by itself will be very brittle.In addition, the olefinic groups of the sulfonated substantially randominterpolymer component provide improved compatibility with a polyolefincore fiber in bicomponent structures. In addition, the ethylene groupscan provide some degree of hydrophobicity to the fiber, keeping it fromdissolving even when all the aromatic rings are sulfonated.

[0088] The absorbent fibers of the present invention can be preparedusing techniques well known in the art including for example, dry lay,wet lay, carding, spin bonding, garnetting, and air laying processes.(See, e.g. U.S. Pat. Nos. 5,108,827, 5,487,943, 4,176,108 and4,814,226). Nonwoven fabrics and articles can be prepared using bindingtechniques including, for example, hot roll, hot press, lamination, hotair bonding, calendar, spray, dip and roll transfer processes. (See,e.g., U.S. Pat. Nos. 5,824,610, 5,593,768, 5,169,580 and 5,244,695).

[0089] For the absorbent fibers of the present invention, the diametercan be widely varied. Fiber diameter can be measured and reported in avariety of fashions. Generally, fiber diameter is measured in denier perfilament. Denier is a textile term that is defined as the grams of thefiber per 9000 meters of that fiber's length. Monofilament generallyrefers to an extruded strand having a denier per filament greater than15, usually greater than 30. Fine denier fiber generally refers to fiberhaving a denier of about 15 or less. Microdenier (aka microfiber)generally refers to fiber having a diameter not greater than about 100micrometers. The fiber denier can be adjusted to suit the capabilitiesof the finished article and as such, would preferably be: from about 0.5to about 30 denier/filament for melt blown; from about 1 to about 30denier/filament for spunbond; and from about 1 to about 20,000denier/filament for continuous wound filament. Nonetheless, preferably,the nominal denier is greater than 37, more preferably greater than orequal to 55 and most preferably greater than or equal to 65. Thesepreferences are due to the fact that typically durable apparel employfibers with deniers greater than or equal to about 40.

[0090] Finishing operations can optionally be performed on the fibers ofthe present invention. For example, the fibers can be texturized bymechanically crimping or forming such as described in Textile Fibers,Dyes, Finishes, and Processes: A Concise Guide, by Howard L. Needles,Noyes Publications, 1986, pp. 17-20.

[0091] The interpolymer compositions used to make the fibers of thepresent invention or the fibers themselves (both prior to or postsulfonation) may also be modified by various cross-linking processesusing curing methods at any stage of the fiber preparation including,but not limited to, before during, and after drawing at either elevatedor ambient temperatures. Such cross-linking processes include, but arenot limited to, peroxide-, silane-, sulfur-, radiation-, or azide-basedcure systems. A full description of the various cross-linkingtechnologies is described in copending U.S. patent application Ser. Nos.08/921,641 and 08/921,642 both filed on Aug. 27, 1997, the entirecontents of both of which are herein incorporated by reference.

[0092] Dual cure systems, which use a combination of heat, moisturecure, and radiation steps, may be effectively employed. Dual curesystems are disclosed and claimed in U.S. patent application Ser. No.536,022, filed on Sep. 29, 1995, in the names of K. L. Walton and S. V.Karande, incorporated herein by reference. For instance, it may bedesirable to employ peroxide crosslinking agents in conjunction withsilane crosslinking agents, peroxide crosslinking agents in conjunctionwith radiation, sulfur-containing crosslinking agents in conjunctionwith silane crosslinking agents, etc.

[0093] The polymer compositions may also be modified by variouscross-linking processes including, but not limited to the incorporationof a diene component as a termonomer in its preparation and subsequentcross linking by the aforementioned methods and further methodsincluding vulcanization via the vinyl group using sulfur for example asthe cross linking agent.

[0094] The fibers of the present invention may be surface functionalizedby methods including, but not limited to, chlorination using chemicaltreatments for permanent surfaces or incorporating a temporary coatingusing the various well known spin finishing processes.

[0095] The fibers comprising the sulfonated substantially randominterpolymers can be essentially in the form of any fibers previouslyknown in the art. This includes the homofil fibers including staplefibers, spunbond fibers or melt blown fibers (using, e.g., systems asdisclosed in U.S. Pat. No. 4,340,563 (Appel et al.), U.S. Pat. No.4,663,220 (Wisneski et al.), U.S. Pat. No. 4,668,566 (Braun), or U.S.Pat. No. 4,322,027 (Reba), all of which are incorporated herein byreference), and gel spun fibers (e.g., the system disclosed in U.S. Pat.No. 4,413,110 (Kavesh et al.), incorporated herein by reference). Staplefibers can be melt spun (i.e., they can be extruded into the final fiberdiameter directly without additional drawing), or they can be melt spuninto a higher diameter and subsequently hot or cold drawn to the desireddiameter using conventional fiber drawing techniques.

[0096] The shape of the fiber is not limited. For example, typical fiberhas a circular cross-sectional shape, but sometimes fibers havedifferent shapes, such as a trilobal shape, or a flat (i.e., “ribbon”like) shape. The absorbent fibers disclosed herein, are not limited bythe shape of the fiber.

[0097] The fibers comprising the sulfonated substantially randominterpolymers can also be used as bonding fibers, especially where theinventive fibers have a lower melting point than the surrounding matrixfibers. In a bonding fiber application, the bonding fiber is typicallyblended with other matrix fibers and the entire structure is subjectedto heat, where the bonding fiber melts and bonds the surrounding matrixfiber. Typical matrix fibers which benefit from use of the inventivefibers disclosed herein include, but are not limited to, poly(ethyleneterephthalate) fibers, cotton fibers, nylon fibers, polypropylenefibers, heterogeneously branched polyethylene fibers, homogeneouslybranched ethylene polymer fibers, linear polyethylene homopolymer fibersand the like and combinations thereof. The diameter of the matrix fibercan vary depending upon the end use application.

[0098] These fibers of the present invention can comprise more than onepolymer, including wettable binder fibers (U.S. Pat. No. 5,894,000);hydrophilic fibers, superabsorbent polymer fibers (U.S. Pat. Nos.5,593,399 and 5,698,480); and the fibers listed in U.S. Pat. No.4,176,108. The teachings of these patents, and all other patents citedherein, are hereby incorporated by reference in their entirety. Mixturesof fibers can also be employed. Examples of common materials used in themanufacture of fibers available for mixing with the fibers of thepresent invention include natural and synthetic materials such as, forexample, polyethylene terephthalate, polyethylene, polypropylene,polyurethane, nylon, rayon, and cotton and other cellulosic materials.

[0099] In an especially preferred embodiment, the absorbent fiberscomprising the sulfonated substantially random interpolymers areconjugated or bicomponent or multi-component fibers (as disclosed inU.S. Pat. Nos. 5,843,063; 5,169,580; 4,634,739; 5,921,973; 4,483,976;and 5,403,444 which are hereby incorporated by reference in theirentirety). The polymer components are usually different from each other,although conjugated fibers may be mono-component fibers. The polymersare arranged in substantially constantly positioned distinct zonesacross the cross-section of the conjugated fibers and extendcontinuously along the length of the conjugated fibers. Theconfiguration of the conjugated fibers of the present invention can be,for example, a sheath/core arrangement (wherein one polymer issurrounded by another), a side by side arrangement, a pie arrangement oran “islands-in-the sea” arrangement. Conjugated fibers are described inU.S Pat. No. 5,108,820 to Kaneko et al.; U.S. Pat. No. 5,336,552 toStrack et al.; and U.S. Pat. No. 5,382,400 to Pike et al., thedisclosures of all of which are incorporated herein by reference. Thefibers comprising the sulfonated substantially random interpolymers ofthe present invention can be in a conjugated configuration, for example,as a core or sheath, or both. Different sulfonated substantially randominterpolymers can also be used independently as the sheath and the corein the same fiber, especially where the sheath component has a lowermelting point than the core component.

[0100] Fabrics and Fabricated Articles

[0101] Fabrics made from such novel absorbent fibers of the presentinvention can include both woven and nonwoven fabrics. Nonwoven fabricscan be made variously, including spunlaced (or hydrodynamicallyentangled) fabrics as disclosed in U.S. Pat. No. 3,485,706 (Evans) andU.S. Pat. No. 4,939,016 (Radwanski et al.), the disclosures of which areincorporated herein by reference; by carding and thermally bondingstaple fibers; by spunbonding continuous fibers in one continuousoperation; or by melt blowing fibers into fabric and subsequentlycalandering or thermally bonding the resultant web. These variousnonwoven fabric manufacturing techniques are well known to those skilledin the art and the disclosure is not limited to any particular method.Other structures made from such fibers are also included within thescope of the invention, including e.g., blends of these novel fiberswith other fibers (e.g., poly(ethylene terephthalate) (PET) or cotton orwool or polyester). For example, nonwoven fabrics of the invention maybe used in filtration applications, medical applications, clean roomapplications, garments, barrier products, sterilization wraps,interlinings, cushioning, CSR wrap, stretchable absorbent materials, andwipes.

[0102] The absorbent articles of the present invention can be utilizedin disposable products which are capable of absorbing significantquantities of body fluids, such as urine and water in body wastes. Sucharticles may be prepared in the form of sanitary napkins and otherfeminine hygiene products, disposable diapers, adult incontinencebriefs, adult incontinence pads and the like.

[0103] In a preferred embodiment of the present invention the sulfonatedsubstantially random interpolymer fibers are used in the construction ofdiapers, as part of the distribution, acquisition and/or surge layersand in the core. (See, e.g., U.S. Pat. Nos. 5,108,827, 5,893,063,5,593,768, 5,646,077, and 5,244,695). Especially preferred absorbentarticles of this invention are disposable diapers. Articles in the formof disposable diapers are fully described in Duncan and Baker, U.S. Pat.No. Re. 26,151, Issued Jan. 31, 1967; Duncan, U.S. Pat. No. 3,592,194,Issued Jul. 13, 1971; Duncan and Gellert, U.S. Pat. No. 3,489,148,Issued Jan. 13, 1970; and Buell, U.S. Pat. No. 3,860,003, Issued Jan.14, 1975; which patents are incorporated herein by reference.

[0104] One means for increasing the liquid retention capabilities ofsuch products is through the addition of superabsorbents, which are alsoreferred to as hydrogels and hydrocolloids. This is particularly true inthe case of diapers, training pants and incontinence garments. As theseproducts have become more and more sophisticated, the manufacturers ofthese products have reduced the amount of wood pulp or fluff in theabsorbent layers of these materials and replaced the fluff with varyingamounts of superabsorbent in the form of particles. As the amount ofsuperabsorbent has increased in these absorbent structures, a problemcalled gel-blocking has arisen. Early superabsorbents were made inparticle form and while being capable of absorbing many times their ownweight in liquid such as water and urine, would not hold their particleor generally spherical shape as they absorbed liquid. Instead, theywould turn into a mushy gel which would swell, fill the voids betweenthe wood pulp fibers and quickly turned the structure into a gelledmess. This is now referred to as gel blocking. The absorbent fibers ofthe present invention may be used as the sole superabsorbent corecomponent or may be used in addition to the aforementioned corecomponents of the prior art to facilitate liquid transport and alleviatethe problem of gell blocking.

[0105] Nonwoven products prepared with the absorbent fibers of theinvention may also be useful in specialty applications such as thepreparation of hygiene articles having patterned component distribution(see, e.g., U.S. Pat. Nos. 5,843,063, 5,593,399 and 5,941,862) andflushable diapers (see, e.g., U.S. Pat. No. 5,770,528).

[0106] Woven fabrics can also be made which comprise the absorbentfibers of the present invention. The various woven fabric-manufacturingtechniques are well known to those skilled in the art and the disclosureis not limited to any particular method. Woven fabrics are typicallystronger and more heat resistant and are thus used typically in durable,non-disposable applications as for example in the woven blends withpolyester and polyester cotton blends. The woven fabrics comprising theabsorbent fibers of the present invention can be used in applicationsincluding but not limited to, upholstery, athletic apparel, carpet,fabrics, bandages. In addition the fibers of the present invention canbe included in the woven fabrics of the prior art (e.g. as staple fibersin existing fabrics) to promote absorbency.

[0107] The novel absorbent fibers described herein also can be used in aspunlaced (or hydrodynamically entangled) process to make novelstructures. For example, U.S. Pat. No. 4,801,482 (Goggans), thedisclosure of which is incorporated herein by reference, discloses asheet which can now be made with the novel fibers/fabric describedherein. Composites that utilize very high molecular weight linearpolyethylene or copolymer polyethylene also benefit from the novelfibers disclosed herein. For example, for the novel fibers that have alow melting point, such that in a blend of the novel fibers and veryhigh molecular weight polyethylene fibers (as described in U.S. Pat. No.4,584,347 by Harpell et al., the disclosure of which is incorporatedherein by reference), the lower melting fibers bond the high molecularweight polyethylene fibers without melting the high molecular weightfibers, thus preserving the high strength and integrity of the highmolecular weight fiber.

[0108] Absorbent and Superabsorbent Foams

[0109] Absorbent and superabsorbent foams have attracted considerableattention as candidates for replacing multiple components of anabsorbent core. They hold the potential of offering some of the sameadvantages sought for film or fiber forms; performing the absorbentfunctions of multiple components of a conventional diaper, not migratingin the product, and not creating dust. Several different approaches tosuperabsorbent polymer foams have been described in the patentliterature. One approach seeks to embed conventional superabsorbentgranules in non-superabsorbent foam. A second option is to utilizecapillary suction forces, instead of or in addition to osmotic pressure,to create an absorbent material.

[0110] The incorporation of a conventional granular superabsorbentpolymer into a foam structure is a relatively obvious extension ofsuperabsorbent polymer technology. For any composite structurecomprising a foam and a superabsorbent polymer to have enhancedperformance, a number of technical challenges must be met. The foam mustconvey the fluid to the superabsorbent polymer particles rapidly andeffectively. As the superabsorbent polymer swells, it must not block thepassage of fluid through the foam, nor should it become detached fromthe foam structure.

[0111] While conventional superabsorbent polymers utilize osmotic forcesto retain aqueous fluids, most other common absorbents depend oncapillary forces, or the tendency of an aqueous fluid to spread and weta high-energy surface. Paper towels, sponges, and cellulose fluffs areexamples of capillary absorbers. Recently there has been a significantamount of activity on microcellular foams as superabsorbent structures,including absorbent materials made using high internal phase-ratioemulsions (HIPEs). An important aspect of these foams is that they areinherently lipophilic, requiring a post-treatment in order to absorbaqueous solutions.

[0112] In one embodiment of the present invention, the sulfonatedsubstantially random interpolymers are used to prepare absorbent foams.The foams can be prepared from the sulfonated substantially randominterpolymers using the methods described herein. Alternatively, thefoams can be prepared from the substantially random interpolymers andthen the resulting foams can then be sulfonated either after or duringthe foam manufacturing process, using the sulfonation processesdescribed herein. In such a post foam sulfonation process, the natureand incorporation of the previously described swelling and sulfonationagents and reaction times can then be tailored to the particular foampreparation.

[0113] Foam forming steps of the process are within the skill in theart. For instance as exemplified by the excellent teachings to processesfor making ethylenic polymer foam structures and processing them in C.P. Park. “Polyolefin Foam”, Chapter 9, Handbook of Polymer Foams andTechnology, edited by D. Klempner and K. C. Frisch, Hanser Publishers,Munich, Vienna, New York, Barcelona (1991), which is incorporated herein by reference.

[0114] The absorbent foam structures of the present invention areoptionally made by a conventional extrusion foaming process. Thestructure is advantageously prepared by heating the sulfonatedsubstantially random interpolymer or blend to form a plasticized or meltpolymer material, incorporating therein a blowing agent to form afoamable gel, and extruding the gel through a die to form the foamproduct. Prior to mixing with the blowing agent, the sulfonatedsubstantially random interpolymer is heated to a temperature at or aboveits glass transition temperature or melting point. The blowing agent isoptionally incorporated or mixed into the melt polymer material by anymeans known in the art such as with an extruder, mixer, blender, or thelike. The blowing agent is mixed with the melt polymer material at anelevated pressure sufficient to prevent substantial expansion of themelt polymer material and to advantageously disperse the blowing agenthomogeneously therein. Optionally, a nucleator is optionally blended inthe melt or dry blended with the sulfonated substantially randominterpolymer prior to plasticizing or melting. The foamable gel istypically cooled to a lower temperature to optimize physicalcharacteristics of the foam structure. The gel is then extruded orconveyed through a die of desired shape to a zone of reduced or lowerpressure to form the foam structure. The zone of lower pressure is at apressure lower than that in which the foamable gel is maintained priorto extrusion through the die. The lower pressure is optionallysuperatmospheric or subatmospheric (vacuum) but is preferably at anatmospheric level.

[0115] In another embodiment, the resulting absorbent foam structure isoptionally formed in a coalesced strand form by extrusion of the polymermaterial through a multi-orifice die. The orifices are arranged so thatcontact between adjacent streams of the molten extrudate occurs duringthe foaming process and the contacting surfaces adhere to one anotherwith sufficient adhesion to result in a unitary foam structure. Thestreams of molten extrudate exiting the die take the form of strands orprofiles, which desirably foam, coalesce, and adhere to one another toform a unitary structure. Desirably, the coalesced individual strands orprofiles should remain adhered in a unitary structure to prevent stranddelamination under stresses encountered in preparing, shaping, and usingthe foam. Apparatuses and method for producing foam structures incoalesced strand form are seen in U.S. Pat. Nos. 3,573,152 and4,824,720, both of which are incorporated herein by reference.

[0116] Alternatively, the resulting absorbent foam structure isconveniently formed by an accumulating extrusion process as described inU.S. Pat. No. 4,323,528, the entire contents of which are incorporatedby reference herein. In another embodiment, the resulting foam structureis formed into non-crosslinked foam beads suitable for molding intoarticles. This process is well taught in U.S. Pat. Nos. 4,379,859 and4,464,484, which are incorporated herein by reference.

[0117] In one modification of the uncrosslinked bead process, styrenemonomer is optionally impregnated into the suspended pellets prior totheir impregnation with blowing agent to form a graft interpolymer withthe sulfonated substantially random interpolymer. Such a process ofmaking such interpolymer beads is described for instance in U.S. Pat.No. 4,168,353, which is incorporated herein by reference.

[0118] The foam beads are conveniently then molded by any means withinthe skill in the art, such as taught for instance in U.S. Pat. Nos.3,504,068 and 3,953,558. and C. P. Park, supra, p. 191, pp. 197-198, andpp. 227-229, the entire contents of all of which are incorporated hereinby reference.

[0119] Blowing agents useful in making the absorbent foam structures ofthe present invention include inorganic agents, organic blowing agentsand chemical blowing agents. Suitable inorganic blowing agents includecarbon dioxide, nitrogen, argon, water, air, nitrogen, and helium.Organic blowing agents include aliphatic hydrocarbons having 1-6 carbonatoms, aliphatic alcohols having 1-3 carbon atoms, and fully andpartially halogenated aliphatic hydrocarbons having 1-4 carbon atoms.Aliphatic hydrocarbons include methane, ethane, propane, n-butane,isobutane, n-pentane, isopentane, neopentane, and the like. Aliphaticalcohols include methanol, ethanol, n-propanol, and isopropanol. Fullyand partially halogenated aliphatic hydrocarbons include fluorocarbons,chlorocarbons, and chlorofluorocarbons. Examples of fluorocarbonsinclude methyl fluoride, perfluoromethane, ethyl fluoride,1,1-difluoroethane (HFC-152a), 1,1,1-trifluoroethane (HFC-143a),1,1,1-2-tetrafluoro-ethane (HFC-134a), pentafluoroethane,difluoromethane, perfluoroethane, 2,2-difluoropropane,1,1,1-trifluoropropane, perfluoropropane, dichloropropane,difluoropropane, perfluorobutane, perfluorocyclobutane. Partiallyhalogenated chlorocarbons and chlorofluorocarbons for use in thisinvention include methyl chloride, methylene chloride, ethyl chloride,1,1,1-trichloroethane, 1,1-dichloro-1 fluoroethane (HCFC-141b), 1-chloro1,1-difluoroethane (HCFC-142b), 1-dichloro-2,2,2-trifluoroethane(HCFC-123) and 1-chloro-1,2,2,2-tetrafluoroethane (HCFC-124). Fullyhalogenated chlorofluorocarbons include trichloromonofluoromethane(CFC-11), dichlorodifluoromethane (CFC-12), trichlorotrifluoroethane(CFC-113), 1,1,1-trifluoroethane, pentafluoroethane,dichlorotetrafluoroethane (CFC-114), chloroheptafluoropropane, anddichlorohexafluoropropane. Chemical blowing agents includeazodicarbonamide, azodiisobutyro-nitrile, barium azodicarboxylate,N,N′-dimethyl-N,N′-dinitrosoterephthalamide, and benzenesulfonhydrazide,4,4-oxybenzene sulfonyl semicarbazide, and p-toluene sulfonylsemicarbazide trihydrazino triazine. Preferred blowing agents includeisobutane, HFC-152a, and mixtures of the foregoing.

[0120] The absorbent foams are optionally perforated to enhance oraccelerate permeation of blowing agent from the foam and air into thefoam. Such perforation is within the skill in the art, for instance astaught in U.S. Pat. Nos. 5,424,016 and 5,585,058, which are incorporatedherein by reference.

[0121] Various additives are optionally incorporated in the resultingfoam structure such as stability control agents, nucleating agents,inorganic fillers, pigments, antioxidants, acid scavengers, ultravioletabsorbers, flame retardants, processing aids, extrusion aids, and thelike.

[0122] A stability control agent is optionally added to the present foamto enhance dimensional stability. Preferred agents include amides andesters of C10-24 fatty acids. Such agents are seen in U.S. Pat. Nos.3,644,230 and 4,214,054, which are incorporated herein by reference.

[0123] In addition, a nucleating agent is optionally added in order tocontrol the size of foam cells. Preferred nucleating agents includeinorganic substances such as calcium carbonate, talc, clay, titaniumoxide, silica, barium sulfate, diatomaceous earth, mixtures of citricacid and sodium bicarbonate, and the like. The amount of nucleatingagent employed may range from about 0.01 to about 5 parts by weight perhundred parts by weight of a polymer resin.

[0124] The resulting foam structure is optionally closed-celled oropen-celled. The open cell content will range from 0 to 100 volumepercent as measured according to ASTM D2856-A.

[0125] The resulting absorbent foam structure is substantiallynoncrosslinked or uncrosslinked, and is optionally is in any physicalconfiguration within the skill in the art, such as extruded sheet, rod,plank, and profiles.

[0126] Compositions of the Absorbent Polymers of the Present Invention

[0127] The starting material substantially random interpolymer prior tosulfonation comprise from about 0.5 to about 65, preferably from about 5to about 65, more preferably from about 10 to about 65 mole percent ofat least one vinyl or vinylidene aromatic monomer and/or aliphatic orcycloaliphatic vinyl or vinylidene monomer and from about 35 to about99.5, preferably from about 35 to about 95, more preferably from about35 to about 90 mole percent of ethylene and/or at least one aliphaticα-olefin having from 3 to about 20 carbon atoms.

[0128] The melt index (I₂) of the starting material substantially randominterpolymer prior to sulfonation is from about 0.01 to about 1000,preferably of from about 0.3 to about 30, more preferably of from about0.5 to about 10 g/10 min.

[0129] The molecular weight distribution (M_(w)/M_(n)) of the startingmaterial substantially random interpolymer prior to sulfonation is fromabout 1.5 to about 20, preferably of from about 1.8 to about 10, morepreferably of from about 2 to about 5.

[0130] The density of the starting material substantially randominterpolymer prior to sulfonation is greater than about 0.930,preferably from about 0.930 to about 1.045, more preferably of fromabout 0.930 to about 1.040, most preferably of from about 0.930 to about1.030 g/cm³.

[0131] The degree of sulfonation of the starting material substantiallyrandom interpolymer is from about 1.5 to about 100, preferably fromabout 15 to about 100, more preferably from about 30 to 100 mol percent(based on the total number of aromatic rings in the initialsubstantially random interpolymer) of mono substituted aromatic ringssubstituted with a sulfonic acid group or a sulfonic acid salt.

[0132] The absorbent polymers compositions of the present inventioncomprise from about 10 to 100, preferably from about 20 to 100, morepreferably from about 50 to 100 wt percent, (based on the combinedweights of this component and the polymer component other than thesulfonated substantially random interpolymer) of one or more sulfonatedsubstantially random interpolymers of ethylene and/or one or moreα-olefins and one or more vinyl or vinylidene aromatic monomers and/orone or more sterically hindered aliphatic or cycloaliphatic vinyl orvinylidene monomers.

[0133] The sulfonated substantially random interpolymers comprise fromabout 35 to about 98.5, preferably from about 35 to about 85, morepreferably from about 35 to about 70 mol percent of repeating unitsderived from ethylene and/or said ox-olefin which comprises at least oneof propylene, 4-methyl-1-pentene, butene-1, hexene-1 or octene-1.

[0134] The sulfonated substantially random interpolymers comprise fromabout 1.5 to about 65 preferably from about 15 to about 65, morepreferably from about 30 to about 65 mol percent of repeating unitsderived from said sulfonated vinyl or vinylidene aromatic monomers.

[0135] The sulfonated substantially random interpolymers comprise from 0to about 63.5, preferably from 0 to about 50, more preferably from 0 toabout 35 mol percent of repeating units derived from vinyl or vinylidenearomatic monomers.

[0136] The sulfonated substantially random interpolymers comprise from 0to about 63.5, preferably from 0 to about 50, more preferably from 0 toabout 35 mol percent of repeating units derived from said stericallyhindered aliphatic or cycloaliphatic vinyl or vinylidene monomers.

[0137] The sulfonated substantially random interpolymers comprise from 0to about 20 preferably, more preferably mol percent of norbornene, or aC₁₋₁₀ alkyl or C₆₋₁₀ aryl substituted norbornene.

[0138] The absorbent polymers compositions of the present invention canalso comprise from 0 to about 90, preferably from 0 to about 80, morepreferably from 0 to about 50 wt percent of at least one polymer otherthan said sulfonated substantially random interpolymer (based on thecombined weights of this component and the substantially randominterpolymer).

[0139] Applications

[0140] Applications for the materials of the present invention includethe various applications for membranes as described in “MembraneTechnology” in The Encyclopedia of Chemical Technology, Vol 16, ppgs135-193, (4^(th) ed, 1995, J. Wiley and Sons Inc., NY) the entirecontents of which are herein incorporated by reference.

[0141] Other applications include modification of petroleum andhydrocarbon-based materials such as oils, asphalts and bitumenousproducts, in which the sulfonation improves the compatibility of thepolymer. Also included are reinforcement of cementitious products by thesulfonated fibers of the present invention. Films and multilayer filmsfor food packaging, and medical applications such as medicine bags,bandages, tapes, casts and the like, as well as delivery systems foragricultural products such as herbicides, pesticicdes and fertiliers aswell as pharmaceutical products or other pharmaceutical applications.Also included are the use of the compositions of the present inventionas binders for the recovery of coal and refractory fines. Also includedare applications using the materials of the present invention as solidacid catalysts including shape selective and optically active catalytictransformations. Others uses include packaging (absorbent fiber used inpackaging in case of spills), food packaging, cable wrap (water blocktape in cables), medical applications (bandages, surgical drapes, spillclean up), apparel (absorbent fiber for improved comfort), controlledrelease fiber (imbibe absorbent fiber with antimicrobial, perfume,antibiotics etc.), absorbent articles for meat trays, absorbent articlesfor personal hygiene such as diapers, sanitary napkins adultincontinence pads, wipes (highly absorbent wipes, dust pickup), softener(sulfonated fiber holds on to fabric softeners and slowly releasesthem), towels with superabsorbing power (staple fibers to be combined incotton yarns and improved water absorption capacity of towels, even inpresence of fabric softeners), and disposable high absorbing towels(staple fibers to be combined with paper/non wovens towels fordisposable applications such as towels for gym clubs, hospitals, etc.)

[0142] The following examples are to illustrate this invention and donot limit it.

EXAMPLES

[0143] Test Methods.

[0144] a) Melt Flow Measurements.

[0145] Unless otherwise stated, the molecular weight of the polymercompositions for use in the present invention is conveniently indicatedusing a melt index measurement according to ASTM D-1238, Condition 190°C./2.16 kg (formally known as “Condition (E)” and also known as I₂) wasdetermined. Melt index is inversely proportional to the molecular weightof the polymer. Thus, the higher the molecular weight, the lower themelt index, although the relationship is not linear.

[0146] b) Styrene Analyses

[0147] Interpolymer styrene content and the concentration of atacticpolystyrene homopolymer impurity in the ESI interpolymers was determinedusing proton nuclear magnetic resonance (¹H NMR). All proton NMR sampleswere prepared in 1,1,2,2-tetrachloroethane-d₂ (tce-d₂). The resultingsolutions contained approximately 1-3 weight percent polymer. Theinterpolymers were weighed directly into 5-mm sample tubes. A 0.75-mlaliquot of tce-d₂ was added by syringe and the tube sealed with atight-fitting cap. The samples were heated at 85° C. to soften theinterpolymer. To provide mixing, the capped samples were occasionallybrought to reflux using a heat gun.

[0148] Proton NMR spectra were accumulated with the sample probe at 80°C., and referenced to the residual protons of tce-d₂ at 5.99 ppm. Datawas collected in triplicate on each sample using the followinginstrumental conditions:

[0149] Sweep width, 5000 hz

[0150] Acquisition time, 3.002 sec

[0151] Pulse width, 8 μsec

[0152] Frequency, 300 mhz

[0153] Delay, 1 sec

[0154] Transients, 16

[0155] The total analysis time per sample was about 10 minutes.

[0156] Initially, a spectrum for a sample of polystyrene (192,000 M_(w))was acquired. Polystyrene has five different types of protons that aredistinguishable by proton NMR. In FIG. 1, these protons are labeled b,branch; α, alpha; o, ortho; m, meta; p, para, as shown in FIG. 1. Foreach repeating unit in the polymer, there are one branch proton,two-alpha protons, two ortho protons, two meta protons and one paraproton.

[0157] The NMR spectrum for polystyrene homopolymer includes a resonancecentered around a chemical shift of about 7.1 ppm, which is believed tocorrespond to the three ortho and para protons. The spectrum alsoincludes another peak centered around a chemical shift of about 6.6 ppm.That peak corresponds to the two meta protons. Other peaks at about 1.5and 1.9 ppm correspond to the three aliphatic protons (alpha andbranch).

[0158] The relative intensities of the resonances for each of theseprotons were determined by integration. The integral corresponding tothe resonance at 7.1 ppm was designated PS_(7.1) below. Thatcorresponding to the resonance at 6.6 ppm was designated PS_(6.6), andthat corresponding to the aliphatic protons (integrated from 0.8-2.5ppm) was designated PS_(al). The theoretical ratio forPS_(7.1):PS_(6.6):PS_(al) is 3:2:3, or 1.5:1:1.5. For atacticpolystyrene homopolymer, all spectra collected had the expected1.5:1:1.5 integration ratio. An aliphatic ratio of 2 to 1 is predictedbased on the protons labeled α and b respectively in FIG. 1. This ratiowas also observed when the two aliphatic peaks were integratedseparately. Further, the ratio of aromatic to aliphatic protons wasmeasured to be 5 to 3, as predicted from theoretical considerations.

[0159] The ¹H NMR spectrum for the ESI interpolymer was then acquired.This spectrum showed resonances centered at about 7.1 ppm, 6.6 ppm andin the aliphatic region. However, the 6.6 ppm peak was relatively muchweaker for the ESI interpolymer than for the polystyrene homopolymer.The relative weakness of this peak is believed to occur because the metaprotons in the ESI copolymer resonate in the 7.1 ppm region. Thus, theonly protons that produce the 6.6 ppm peak are meta protons associatedwith atactic polystyrene homopolymer that is an impurity in the ESI. Thepeak centered at about 7.1 ppm thus includes ortho, meta and paraprotons from the aromatic rings in the ESI interpolymer, as well as theortho and para protons from the aromatic rings in the polystyrenehomopolymer impurity. The peaks in the aliphatic region includeresonances of aliphatic protons from both the ESI interpolymer and thepolystyrene homopolymer impurity.

[0160] Again, the relative intensities of the peaks were determined byintegration. The peak centered around 7.1 ppm is referred to below asI_(7.1), that centered around 6.6 ppm is I_(6.6) and that in thealiphatic regions is I_(al).

[0161] I_(7.1) includes a component attributable to the aromatic protonsof the ESI interpolymer and a component attributable to the ortho andpara protons of the aromatic rings of the polystyrene homopolymerimpurity. Thus,

I _(7.1) =I _(c7.1) +I _(ps7.1)

[0162] where I_(c7.1) is the intensity of the 7.1 ppm resonanceattributable to the aromatic protons in the interpolymer and I_(ps7.1)is the intensity of the 7.1 ppm resonance attributable to the ortho andmeta protons of the polystyrene homopolymer.

[0163] From theoretical considerations, as confirmed by the ¹H NMRspectrum of the polystyrene homopolymer, the intensity of the 7.1 ppmresonance attributable to the polystyrene homopolymer impurity(I_(ps7.1)), equals 1.5 times the intensity of the 6.6 ppm resonance.This provides a basis for determining I_(c7.1) from measured values, asfollows:

I _(c7.1) =I _(7.1)−1.5(I _(6.6)).

[0164] Similarly, I_(al) can be resolved into resonances attributable tothe ESI and the polystyrene homopolymer impurity using the relationship

I _(al) =I _(cal) +I _(psal)

[0165] wherein I_(cal) is the intensity attributable to the aliphaticprotons on the interpolymer and I_(psal) is the intensity attributableto the aliphatic protons of the polystyrene homopolymer impurity. Again,it is known from theoretical considerations and the spectrum from theatactic polystyrene homopolymer that I_(psal) will equal 1.5 timesI_(6.6). Thus the following relationship provides a basis fordetermining I_(cal) from measured values:

I _(cal) =I _(al)−1.5(I _(6.6)).

[0166] The mole percent ethylene and styrene in the interpolymer arethen calculated as follows:

s _(c) =I _(c7.1)/5

e _(c)=(I _(cal)−(3×s _(c)))/4

E=e _(c)/(s _(c) +e _(c)), and

S=s _(c)/(s _(c) +e _(c)),

[0167] wherein E and S are the mole fractions of copolymerized ethyleneand styrene, respectively, contained in the interpolymer.

[0168] Weight percent ethylene and styrene were calculated using theequations: $\begin{matrix}{{{Wt}\quad \% \quad E} = \frac{100\quad \% \quad*\quad 28\quad E}{\left( {{28\quad E} + {104\quad S}} \right)}} \\{{{Wt}\quad \% \quad S} = {\frac{100\quad \% \quad*104\quad S}{\left( {{28\quad E} + {104\quad S}} \right)}.}}\end{matrix}{\quad \quad}{and}$

[0169] The weight percent of polystyrene homopolymer impurity in the ESIsample was then determined by the following equation:${{Wt}\quad \% \quad {PS}} = {\frac{100\quad \% \quad*{Wt}\quad \% \quad S*\left( {{I_{6.6}/2}S} \right)}{100 - \left\lbrack {{Wt}\quad \% \quad S*\left( {{I_{6.6}/2}S} \right)} \right\rbrack}.}$

[0170] The total styrene content was also determined by quantitativeFourier transform infrared spectroscopy (FTIR).

[0171] Polymer Components Used in the Examples

[0172] PP1 is INSPIRE™ H700-12 polypropylene (a trademark of andavailable from The Dow Chemical Company) having a melt index (ASTMD-1238, Condition 230° C./2.16 kg) of 12 g/10 min

[0173] Preparation of the Ethylene/Styrene Interpolymer, ESI 2.

[0174] Preparation of Catalyst B;(1H-cyclopenta[l]phenanthrene-2-yl)dimethyl(t-butylamido)-silanetitanium1,4-diphenylbutadiene).

[0175] 1) Preparation of lithium 1H-cyclopenta[l]phenanthrene-2-yl

[0176] To a 250 ml round bottom flask containing 1.42 g (0.00657 mole)of 1H-cyclopenta[l]phenanthrene and 120 ml of benzene was addeddropwise, 4.2 ml of a 1.60 M solution of n-BuLi in mixed hexanes. Thesolution was allowed to stir overnight. The lithium salt was isolated byfiltration, washing twice with 25 ml benzene and drying under vacuum.Isolated yield was 1.426 g (97.7 percent). 1H NMR analysis indicated thepredominant isomer was substituted at the 2 position.

[0177] 2) Preparation of(1H-cyclopenta[l]phenanthrene-2-yl)dimethylchlorosilane

[0178] To a 500 ml round bottom flask containing 4.16 g (0.0322 mole) ofdimethyldichlorosilane (Me₂SiCl₂) and 250 ml of tetrahydrofuran (THF)was added dropwise a solution of 1.45 g (0.0064 mole) of lithium1H-cyclopenta[l]phenanthrene-2-yl in THF. The solution was stirred forapproximately 16 hours, after which the solvent was removed underreduced pressure, leaving an oily solid which was extracted withtoluene, filtered through diatomaceous earth filter aid (Celite™),washed twice with toluene and dried under reduced pressure. Isolatedyield was 1.98 g (99.5 percent).

[0179] 3) Preparation of(1H-cyclopenta[l]phenanthrene-2-yl)dimethyl(t-butyl amino)silane

[0180] To a 500 ml round bottom flask containing 1.98 g (0.0064 mole) of(1H-cyclopenta[l]phenanthrene-2-yl)dimethylchlorosilane and 250 ml ofhexane was added 2.00 ml (0.0160 mole) of t-butylamine. The reactionmixture was allowed to stir for several days, then filtered usingdiatomaceous earth filter aid (Celite™), washed twice with hexane. Theproduct was isolated by removing residual solvent under reducedpressure. The isolated yield was 1.98 g (88.9 percent).

[0181] 4) Preparation of dilithio(1H-cyclopenta[l]phenanthrene-2-yl)dimethyl(t-butylamido)silane

[0182] To a 250 ml round bottom flask containing 1.03 g (0.0030 mole) of(1H-cyclopenta[l]phenanthrene-2-yl)dimethyl(t-butylamino)saline) and 120ml of benzene was added dropwise 3.90 ml of a solution of 1.6 M n-BuLiin mixed hexanes. The reaction mixture was stirred for approximately 16hours. The product was isolated by filtration, washed twice with benzeneand dried under reduced pressure. Isolated yield was 1.08 g (100percent).

[0183] 5) Preparation of(1H-cyclopenta[l]phenanthrene-2-yl)dimethyl(t-butylamido)silanetitaniumdichloride

[0184] To a 250 ml round bottom flask containing 1.17 g (0.0030 mole) ofTiCl₃.3THF and about 120 ml of THF was added at a fast drip rate about50 ml of a THF solution of 1.08 g of dilithio(1H-cyclopenta[l]phenanthrene-2-yl)dimethyl(t-butylamido)silane. Themixture was stirred at about 20° C. for 1.5 h at which time 0.55 gm(0.002 mole) of solid PbCl₂ was added. After stirring for an additional1.5 h the THF was removed under vacuum and the residue was extractedwith toluene, filtered and dried under reduced pressure to give anorange solid. Yield was 1.31 g (93.5 percent).

[0185] 6) Preparation of(1H-cyclopenta[l]phenanthrene-2-yl)dimethyl(t-butylamido)silanetitanium1,4-diphenylbutadiene

[0186] To a slurry of(1H-cyclopenta[l]phenanthrene-2-yl)dimethyl(t-butylamido) silanetitaniumdichloride (3.48 g, 0.0075 mole) and 1.551 gm (0.0075 mole) of1,4-diphenylbutadiene diphenyllbutadiene in about 80 ml of toluene at70° C. was add 9.9 ml of a 1.6 M solution of n-BuLi (0.0150 mole). Thesolution immediately darkened. The temperature was increased to bringthe mixture to reflux and the mixture was maintained at that temperaturefor 2 hrs. The mixture was cooled to about −20° C. and the volatileswere removed under reduced pressure. The residue was slurried in 60 mlof mixed hexanes at about 20° C. for approximately 16 hours. The mixturewas cooled to about −25° C. for about 1 hour. The solids were collectedon a glass frit by vacuum filtration and dried under reduced pressure.The dried solid was placed in a glass fiber thimble and solid extractedcontinuously with hexanes using a Soxhlet extractor. After 6 hours acrystalline solid was observed in the boiling pot. The mixture wascooled to about −20° C., isolated by filtration from the cold mixtureand dried under reduced pressure to give 1.62 g of a dark crystallinesolid. The filtrate was discarded. The solids in the extractor werestirred and the extraction continued with an additional quantity ofmixed hexanes to give an additional 0.46 g of the desired product as adark crystalline solid.

[0187] Polymerization

[0188] ESI #'s 1-2 were prepared in a continuously operating loopreactor (36.8 gal). An Ingersoll-Dresser twin screw pump provided themixing. The reactor ran liquid full at 475 psig (3,275 kPa) with aresidence time of approximately 25 minutes. Raw materials andcatalyst/cocatalyst flows were fed into the suction of the twin screwpump through injectors and Kenics static mixers. The twin screw pumpdischarged into a 2 inch diameter line which supplied twoChemineer-Kenics 10-68 Type BEM Multi-Tube heat exchangers in series.The tubes of these exchangers contained twisted tapes to increase heattransfer. Upon exiting the last exchanger, loop flow returned throughthe injectors and static mixers to the suction of the pump. Heattransfer oil was circulated through the exchangers' jacket to controlthe loop temperature probe located just prior to the first exchanger.The exit stream of the loop reactor was taken off between the twoexchangers. The flow and solution density of the exit stream wasmeasured by a Micro-Motion™ mass flow meter.

[0189] Solvent feed to the reactor was supplied by two differentsources. A fresh stream of toluene from an 8480-S-E Pulsafeeder™diaphragm pump with rates measured by a Micro-Motion™ mass flow meterwas used to provide flush flow for the reactor seals (20 lb/hr (9.1kg/hr). Recycle solvent was mixed with uninhibited styrene monomer onthe suction side of five 8480-5-E Pulsafeeder™ diaphragm pumps inparallel. These five Pulsafeeder™ pumps supplied solvent and styrene tothe reactor at 650 psig (4,583 kPa). Fresh styrene flow was measured bya Micro-Motion™ mass flow meter, and total recycle solvent/styrene flowwas measured by a separate Micro-Motion™ mass flow meter. Ethylene wassupplied to the reactor at 687 psig (4,838 kPa). The ethylene stream wasmeasured by a Micro-Motion™ mass flow meter. A Brooks flowmeter/controller was used to deliver hydrogen into the ethylene streamat the outlet of the ethylene control valve.

[0190] The ethylene/hydrogen mixture combined with the solvent/styrenestream at ambient temperature. The temperature of the entire feed streamas it entered the reactor loop was lowered to 2° C. by an exchanger with−10° C. glycol on the jacket. Preparation of the three catalystcomponents took place in three separate tanks. Fresh solvent andconcentrated catalyst/cocatalyst premix were added and mixed into theirrespective run tanks and fed into the reactor via variable speed680-S-AEN7 Pulsafeeder™ diaphragm pumps. As previously explained, thethree component catalyst system entered the reactor loop through aninjector and static mixer into the suction side of the twin screw pump.The raw material feed stream was also fed into the reactor loop throughan injector and static mixer downstream of the catalyst injection pointbut upstream of the twin screw pump suction.

[0191] Polymerization was stopped with the addition of catalyst kill(water mixed with solvent) into the reactor product line after theMicro-Motion™ mass flow meter measuring the solution density. A staticmixer in the line provided dispersion of the catalyst kill and additivesin the reactor effluent stream. This stream next entered post reactorheaters that provided additional energy for the solvent removal flash.This flash occurred as the effluent exited the post reactor heater andthe pressure was dropped from 475 psig (3,275 kPa) down to 450 mmHg (60kPa) of absolute pressure at the reactor pressure control valve.

[0192] This flashed polymer entered the first of two hot oil jacketeddevolatilizers. The volatiles flashing from the first devolatizer werecondensed with a glycol jacketed exchanger, passed through the suctionof a vacuum pump, and were discharged to the solvent andstyrene/ethylene separation vessel. Solvent and styrene were removedfrom the bottom of this vessel as recycle solvent while ethyleneexhausted from the top. The ethylene stream was measured with aMicro-Motion™ mass flow meter. The measurement of vented ethylene plus acalculation of the dissolved gases in the solvent/styrene stream wereused to calculate the ethylene conversion. The polymer and remainingsolvent separated in the devolatilizer was pumped with a gear pump to asecond devolatizer. The pressure in the second devolatizer was operatedat 5 mmHg (0.7 kPa) absolute pressure to flash the remaining solvent.This solvent was condensed in a glycol heat exchanger, pumped throughanother vacuum pump, and exported to a waste tank for disposal. The drypolymer (<1000 ppm total volatiles) was pumped with a gear pump to anunderwater pelletizer with 6-hole die, pelletized, spin-dried, andcollected in 1000 lb boxes. TABLE 1 Preparation Conditions for ESI 2*Reactor Solvent Ethylene Hydrogen Styrene Ethylene Temp Flow Flow FlowFlow Conversion B/Ti MMAO^(c)/ Co- ESI # ° C. lb/hr lb/hr sccm lb/hrpercent Ratio TI Ratio Catalyst Catalyst ESI 2 58 308 34 0 263 97.9 4.08.0 A B

[0193] TABLE 2 Properties of ESI #'s 1 and 2 Copolymer ActacticCopolymer Styrene Styrene Polystyrene I₂ ESI # (wt percent) (molpercent) (wt percent) (g/10 min) ESI 1 75 45 N/A 1.0 ESI 2 77 48 8.4 1.1

[0194] As a preliminary to sulfonation, a series of experiments wereperformed in order to determine which solvents swell the substantiallyrandom interpolymers, and over what time period, a sample of ESI 1extruded film (5 mil thick) were cut into 25 mm diameter disks.Individual disks were weighed to the nearest milligram and exposed to anexcess of liquid solvent (cyclohexane, hexane, Isopar™ C, and Isopar™ M,the latter two both products and registered trademarks of ExxonChemical) in small glass culture dishes. At various time intervals, thedisks were removed with tweezers, dabbed to remove surface bulk solventwith an absorbent wiper, and weighed. The percent weight increase fromsolvent absorption was calculated and plotted versus time (Table 1).From these data it is clear that cyclohexane causes a rapid swelling ofthe polymer composition, followed by hexane, Isopar™ C and Isopar™ M.This allows tailoring of the swelling agent to the residence time of thesulfonation process, and allows sulfonation in either a continuous (lowresidence time therefore requires rapid swelling) or batch (longerresidence time, slower swelling processes available) process.

Example 1a, b, and c

[0195] Disks (5 mil thick; 25 mm diameter) prepared from extruded filmof ESI 1 were placed in 4 ounce glass vials followed by 25 ml ofswelling solvents (hexanes, Isopar C, Isopar M). The disks were allowedto swell for 15 minutes; followed by addition of an equivalent volume of30 percent oleum. The oleum formed a separate lower phase to theswelling solvent; the disk remained at the interface between the twofluids. After 5 minutes, the disks were removed with tweezers from thevial and-immersed into 1 Normal aqueous sodium hydroxide in a beaker.Immediate, significant expansion (1.25-1.75× original diameter) of thedisk resulted with voids observed in the core of the disk. The samplessoaked in the caustic solution for 10 minutes followed by soaking indeionized water for 10 minutes. The disks were then placed in smallglass petri dishes and dried at ambient temperature for 15 hours,followed by weighing.

[0196] Excess deionized water was added to the dried sulfonated disks inthe petri dishes (total-immersion) for 30 minutes, followed by placingeach swollen disk between several plies of absorbent towels and pressurefrom two fingers (approximately one kilogram) applied to the disks. Thissurface water removal process was repeated with fresh towels until notransfer of water was observed on the towels (2-3×). The samples wereweighed and percent increase in water weight determined (Table 3). TABLE3 Percent Increase in Water Weight Example No. Solvent Percent WaterGain 1a Hexanes 40 1b Isopar C 182 1c Isopar M 26

Example 2a, b, c

[0197] Using procedure as described in Example 1, three ESI 1 disks(Examples 2 a,b,c) were exposed to 15 minutes of hexane solvent followedby 5, 10, and 15 minutes of 30 percent oleum exposure, respectively.After neutralization and drying, the weight gain was 7, 18, and 24percent, respectively. Using procedure as described in Example 1,sulfonated disks (Exs 2a,b,c), after water exposure gained 109, 143, and231 percent weight, respectively. The percent weight increase fromsulfonation/neutralization versus water uptake is shown in Table 4.TABLE 4 Percent Weight Increase From Sulfonation/Neutralization VersusWater Uptake percent percent Mol percent Example weight gainconversion^(a) sulfonated styrene content 2a 7 10 4.5 2b 18 24 10.8 2c24 33 15.0

Example 3a, b, and c

[0198] A round bicomponent fiber (1000 Denier; 72 monofilaments;tenacity=2.5 g/denier) was prepared by coextruding 30 wt percentpolypropylene (PP1) as the core; and 70 wt percent ESI 2 as the shell.The fibers were fabricated using two 1.25 inch diameter extruders whichfed two gear pumps each pumping at a rate of 6 cm³/rev. The gear pumpspushed the material through a spin pack containing a filter and amultiple hole spinneret. The spin head temperature was typically fromabout 285° C., and varied depending upon the melting point anddegradation temperature of the polymer components being spun. Generallythe higher the molecular weight of the polymers, the higher the melttemperature. Quench air (about 10° C.) was used to help the melt spunfibers cool. The quench air was located just below the spinneret andblows air perpendicularly across the length of the fibers as they areextruded. The fibers were collected on a series of godet rolls toproduce the yarn. The first godet located about 2.5 meters below thespinneret die and having a diameter of about 6 inches (15.24 cm).

[0199] The fiber was tested on an Instron tensile testing deviceequipped with a small plastic jaw on the cross-head (the jaw has aweight of about six gms) and a 500 gram load cell. The jaws are set 1inch (2.54 cm) apart. The cross head speed is set at 5 inches/minute(12.7 cm/minute). A single fiber is loaded into the Instron jaws fortesting. The fiber is then stretched to 100 percent of strain (i.e., itis stretched another 1 inch), where the tenacity is recorded. The fiberis allowed to return to the original Instron setting (where the jaws areagain 1 inch apart) and the fiber is again pulled. At the point wherethe fiber begins to provide stress resistance, the strain is recordedand the percent permanent set is calculated. Thus, a fiber pulled forthe second time which did not provide stress resistance (i.e., pull aload) until it had traveled 0.1 inches (0.25 cm) would have a percentpermanent set is of 10 percent, i.e., the percent of strain at which thefiber begins to provide stress resistance. The numerical differencebetween the percent permanent set and 100 percent is known as thepercent elastic recovery. Thus, a fiber having a permanent set of 10percent will have a 90 percent elastic recovery. After recording percentpermanent set, the fiber is pulled to 100 percent strain and thetenacity recorded. The fiber pulling process is repeated several times,with the percent permanent set recorded each time and the 100 percentstrain tenacity recorded as well. Finally, the fiber is pulled to itsbreaking point and the ultimate breaking tenacity and elongationrecorded.

[0200] The tow was cut into 1.5-2.5 cm lengths, then place in a WaringBlender, combined with water (ca 500 grams water/100 grams chopped tow)and stirred at high speed for 2 minutes. The fibrillated chopped tow wasthen dried in a forced air oven overnight at 50° C. Fibrillated choppedtow was placed into three 6 inch long by 1 inch diameter open cylindermade from coarse stainless screen material. The screens were thensequentially (as defined below) immersed in a series of beakerscontaining excess hexane swelling agent, 30 percent oleum, 100 percentsulfuric acid, 50 percent sulfuric acid, 1 normal aqueous sodiumhydroxide for the indicated times.

[0201] All samples were then filtered on a coarse glass filter andwashed with excess deionized water, followed by drying overnight at 50°C. in a forced air oven to constant weight. The samples were thenevaluated for moisture gain using the procedure as described in Example2. The sulfonation times and moisture gain data are summarized in Table5. TABLE 5 Sulfonation Times and Moisture Gain Data 30 percent 100percent 50 percent Hexane oleum Sulfuric Acid Sulfuric Acid Aq. NaOHMoisture Gain Example (sec) (sec) (sec) (sec) (min) (percent) 3a 0 30 3030 2 90 3b 0 60 30 30 2 150 3c 20 20 30 30 2 520

What is claimed is:
 1. A bicomponent fiber comprising an inner core andan outer sheath; wherein said inner core or said outer core sheath cancomprises one or more sulfonated substantially random interpolymerswherein said bicomponent fiber can absorb at least 50% of the totalweight of the sulfonated substantially random interpolymers of water. 2.A bicomponent fiber comprising an inner core and an outer sheath ofclaim 2 wherein; (A) said inner core comprises from 25 to 80 wt percent(based on the total fiber weight) of one or more propylene hompolymersor copolymers; and (B) said outer sheath comprises from 20 to 75 wtpercent (based on the total fiber weight) of a composition comprising 1)from 10 to 100 wt percent of one or more sulfonated substantially randominterpolymers comprising units derived from; a) from 35 to 98.5 molpercent ethylene and/or one or more alpha olefins; b) from 1.5 to 65 molpercent of one or more sulfonated vinyl aromatic monomers which are monosubstituted with either a sulfonic acid group or a sulfonic acid salt;c) from 0 to 63.5 mol percent of one or more vinyl aromatic monomers;and 2) from 0 to 90 wt percent of one or more polymers other than saidsulfonated substantially random interpolymer, wherein said bicomponentfiber is able to absorb at least 50% of the total sulfonatedsubstantially random interpolymer of the outer sheath weight of water.3. A bicomponent fiber of claim 2 wherein; A) said inner core comprisesfrom 25 to 80 wt percent (based on the total fiber weight) of one ormore propylene hompolymers or copolymers; and B) said outer sheathcomprises from 20 to 75 wt percent (based on the total fiber weight) ofa composition comprising 1) from 10 to 50 wt percent of one or moresulfonated substantially random interpolymers comprising units derivedfrom; a) from 35 to 98.5 mol percent ethylene and/or one or more alphaolefins; b) from 1.5 to 65 mol percent of one or more sulfonated vinylaromatic monomers which are mono substituted with either a sulfonic acidgroup or a sulfonic acid salt; c) from 0 to 63.5 mol percent of one ormore vinyl aromatic monomers; and 2) from 50 to 90 wt percent of one ormore polymers other than said sulfonated substantially randominterpolymer.
 4. The bicomponent fiber of claim claims 1-3, wherein thesheath has a higher softening and melting point than the core material.5. The bicomponent fiber of claim claims 1-3, wherein the sheathmaterial has a lower softening and melting point than the core material.6. An absorbent fabricated article comprising 1) one or more sulfonatedsubstantially random interpolymers comprising units derived from; a)from 35 to 98.5 mol percent ethylene and/or one or more alpha olefins;b) from 1.5 to 65 mol percent of one or more sulfonated vinyl aromaticmonomers; c) from 0 to 63.5 mol percent of one or more vinyl aromaticmonomers; and 2) one or more other polymers, wherein said absorbentfabricated article is able to absorb at least 50% of the total polymerweight of water.
 7. The absorbent fabricated article of claim 6 is inthe form of a diaper, sanitary napkins or an adult incontinence article.8. The absorbent fabricated article of claim 7, wherein the articlecomprises at least one acquisition distribution layer, a binder materialor a plurality of binder fibers, an absorbent core material, or atopsheet/backsheet.
 9. The absorbent fabricated article of claim 8,wherein the absorbent core material comprises multilobal shaped fibersto provide wicking.
 10. The absorbent fabricated article of claim 8,wherein the acquisition distribution layer comprises a foam material ornonwoven material.
 11. The absorbent fabricated article of claim 8,wherein the acquisition distribution layer comprises a foam material anda nonwoven material.
 12. The absorbent fabricated article of claimclaims 10 and 11, wherein the nonwoven material comprises carded, airlaid, or wet laid structures from staple fibers.
 13. The absorbentfabricated article of claim claims 10 and 11, wherein the nonwovenmaterial comprises curly, self crimping, bicomponent, multicomponent,tip trilobal, bonded multiconstituent, microfiber, capillary or hollowfibers.
 14. The absorbent fabricated article of claim claims 10 and 11,wherein the nonwoven material comprises surface treated fibers.
 15. Theabsorbent fabricated article of claim 14, wherein the surface treatedfibers are prepared by a surface treatment which includes plasma,corona, sulfonation or azide treatment.
 16. A method of absorbing anaqueous liquid comprising the steps of: placing the fabricated articleof claim 6 in contact with an aqueous liquid.